New Insights in the Treatment of Waste Water with Graphene: Dual-Site Adsorption by Sodium Dodecylbenzenesulfonate

Abstract

For the adsorption of sodium dodecylbenzenesulfonate (SDBS) in aqueous solution on reduced graphene oxide (rGO), it is demonstrated that the dual-site mechanism is strongly favored over the conventional single-site one. The dual-site adsorption isotherm is derived, and regression analysis is successfully applied to experimental UV−vis data (1 g L −1 rGO; 298−318 K; 100−900 mg L −1 SDBS; pH: 4−11), considering reparametrization to minimize the correlation between the parameter estimates (dual site: ΔH°= −37.1 ± 1.3 kJ mol −1 ; ΔS°= 35.5 ± 4.1 J mol −1 K −1 ; q ∞ = 546.9 ± 8.6 mg SDBS g rGO −1). A temperature of 298 K is identified as the optimal operating temperature with contact times of ca. 30 h (700 mg L −1 SDBS). An improved regression analysis strategy, carefully selecting only low contact times (maximal 10 h), allowed assessment of the dual-site adsorption and desorption coefficient as (1.2 ± 0.3) × 10 −4 L mg SDBS −1 h −1 and (2.8 ± 0.7) × 10 −3 h −1 . Moreover, by the additional presence of sodium chloride (1.2 × 10 4 mg L −1 ), a much lower contact time of ca. 10 h can be selected to ensure an as good as complete SDBS removal, highlighting the potential of the SDBS/rGO system for wastewater treatment.

Agar Aerogel Containing Small-Sized Zeolitic Imidazolate Framework Loaded Carbon Nitride: A Solar-Triggered Regenerable Decontaminant for Convenient and Enhanced Water Purification

“…All of the parameters of single-site adsorption (Figure S10), dual-site adsorption (Figure a), and Freundlich (Figure S11) models are summarized in Table S2. The adsorption data of CR on 50%-aerogel is well fitted with dual-site adsorption model with higher R 2 values than those of single-site adsorption and Freundlich model, proving that the combination of CR molecules with aerogels is dual-site adsorption . According to the calculated data from two-side adsorption model, the maximum adsorption capacity of Hgel-50 is 287.35 mg g –1 .…”

“…It is also further verified that the adsorption process includes two phases, namely, surface diffusion and intraparticle diffusion. The experimental data were then analyzed by single-site adsorption, dual-site adsorption, and Freundlich isotherm models, displayed as eqs , , and , respectively. Here, the Q e and C e are the adsorption capacity of CR and the concentration of CR at equilibrium, respectively. The parameter Q max is the maximum adsorption capacity of adsorption isotherm.…”

“…k p and C represent the diffusion rate constant of intraparticle and the thickness of boundary layer, respectively. Importantly, the fundamentals behind pseudo-second-order equation ensure its validity just under intermediate reaction time and in the case that desorption process is insignificant . Therefore, pseudo-second-order kinetics analysis at lower time was properly conducted (Figures S15 and b) .…”

Polyacrylonitrile/α‐Fe2O3 Hybrid Photocatalytic Composite Adsorbents for Enhanced Dye Removal

“…This process follows two major steps, namely, a fast adsorption stage occurs in the first 30 min of the process followed by a rate‐determining stage. After 200 min, the MB concentration is fixed over time which means reaching to the equilibrium point . It is worth mentioning that the number of available active sites on the PAN/ α ‐Fe 2 O 3 hybrid adsorptive composite drops by approaching to the equilibrium point as a consequence of MB coverage on the adsorbent surface , .…”

A detailed mechanistic study of bulk MADIX of styrene and its chain extension

“…86 For a detailed description of the regression analysis procedure, the reader is referred to earlier work. 87,88 The transfer coefficient k -tr,0 could be neglected based on preliminary simulations (see section S12 of the ESI †), indicating that reaction of R 0 radicals with monomer is strongly preferred over reaction with R o X. Similarly, exchange between conventional initiator radicals (I) and R 0 X is kinetically insignificant as the addition of monomer to I is sufficiently fast (see section S13 of the ESI †).…”